Clocks which make some use of gravity are known. An ordinary pendulum clock uses gravity in connection with regulating its periodicity, but displays time typically with a dial device. The device of German Patent DE 3,135,859 works by the force of gravity on a body containing a viscous fluid, and requires supplying an inclined support with timing markings on the support. Previous devices have not provided a clock which continually positions an indicator of local time in a preferred orientation. Previous non-dial, gravity-operated clocks have typically required an extended area for containing and operating the clock. Accordingly, it would be advantageous to provide a clock which rolls or rotates to display local time in a preferred orientation. It would be further advantageous to provide a clock which rotates or rolls within a constrained region.